The present invention relates to a vacuum processing apparatus for processing with plasma a sample in a processing chamber within a vacuum vessel, and more particularly to a vacuum processing apparatus provided with a transfer chamber within whose evacuated inside a sample is transferred and a processing chamber to communicate with each other to form a passage within which the sample is to pass.
For an apparatus such as the one referred to above, especially for a processing apparatus which is provided inside with at least one vessel having a processing chamber for processing with a plasma a sample to be processed, such as a semiconductor wafer or substrate, in an evacuated processing chamber, improvement of the efficiency of processing the substrate to be processed has been called for as the processing has become finer and more precise. To meet this requirement, in recent years so-called multi-chamber type apparatuses, each having plural processing chambers connected to it, have been developed to enable one sample to go through plural steps in a single apparatus or plural samples to be processed in parallel and thereby to enhance the efficiency of processing.
In such apparatus which is provided with plural processing chambers or processing vessels and performs processing, each of the processing chambers is connected to a transfer chamber whose internal gas and pressure can be controlled to be reduced and which is equipped with a robot arm or the like for transferring the substrate.
In this configuration, the substrate either not yet processed or already processed is carried from one processing chamber to another within the transfer chamber whose inside is reduced in pressure or loaded with inert gas, and the processing is continuously carried on without allowing the substrate to come into contact with the external atmosphere. Therefore, the contamination of the substrate is restrained, and the yield and efficiency of the processing are enhanced. Also, the time for raising or reducing the pressure within the processing chamber and the transfer chamber can be fully or partly saved, resulting in a shortened processing sequence and enhanced processing efficiency, with the overall labor and time taken to process the substrate reduced.
Such apparatus, in which each processing vessel is detachable from the apparatus itself or the transfer chamber, can be adapted to a new processing process by replacing, or altering the combination of, its processing vessels without replacing the apparatus as such, and this feature contributes to keeping low the cost of manufacturing the product by processing its substrate.
Between the processing chamber and the transfer chamber in each processing vessel of such an apparatus, a passage to establish communication between them is arranged so that samples can be transferred between the two chambers. Usually, such a passage is arranged on a side wall of a processing vessel or a transfer vessel having a transfer chamber within, and a sample held by a robot arm, which is the means of transferring, is exchanged between the processing chamber and the transfer chamber past the inside of the passage penetrating adjacently arranged the side walls.
Known techniques regarding a plasma processing apparatus equipped with such a detachable processing vessel include what is disclosed in Japanese Translation of Unexamined PCT Application No. 2002-520811. According to this known art, a chamber in which semiconductor wafers are processed is linked to cluster tools, and a substrate is transferred into and out of the substrate processing position arranged in the chamber through a slit passage within the chamber body. This slit passage is opened and closed with at least one valve door.
As the above-described conventional technique involves a lack of consideration in the following respect, it is beset with a problem.
Namely, while a substrate, which is the sample to be processed, is processed with a plasma formed by the application of an electric field or a magnetic field to processing gas supplied into the processing chamber, the excited processing gas, processing products or unused processing gas remain around the sample even after the end of the processing, and these gases and products move together with the sample when the sample is transferred outside.
Some of these gases and products stick to the surrounding wall faces of the apparatus during the transfer, and they are particularly apt to stick to the internal walls of the passage between the processing chamber and the transfer chamber, which is often formed in a size close to those of the sample and the robot arm, which is the means of transferring, on account of the limitation of apparatus size.
As a result, mutual actions between reactions with the highly reactive gases and the sticking of the products occur on the wall faces of this passage to invite the progress of contamination and degeneration of the wall faces, which have to be cleaned when the progress has reached an intolerable extent.
Since such a passage is constrained in size as mentioned above, it takes much labor and time to clean and otherwise maintain it. This eventually sacrifices the operable period of the apparatus, inviting detrimental effects to the efficiency of its operation and that of processing, but the above-described known art ignores this aspect.
Furthermore, this problem results in forcing the maintenance worker to do the job in an improper body position for a long time. Another trouble is that, while the products are removed by wet wiping-off, some of the contaminants tend to escape the wiping-off, which involves accidental damaging of the internal wall faces of the passage and deterioration in maintenance accuracy. These problems have not been taken into consideration either.